I like the idea of modern parables. This is a good one
I like that our Jane Doe starts out as a normal person - no disorder or mental issues. I think that makes the eventual anorexia more effective than is she had wandered in already unhealthily thin.
I think you lose it a little here:
That was when she began to decay inside. Absolute power corrupts absolutely; there was no way Jane could escape the way her crown was thrust upon her. I don't really think you need to throw in the "power corrupts" point - things are already a bit heavy handed in the "healthy body image" message. I like that she becomes lazy over time and has to work for their love again, but I'd leave power out of it completely.
Other than that though, I like the matter-of-fact tone you chose to take with it. It gives it a fable-esque quality that's very fitting (and that fable-esque quality is what keeps it from being
too heavy handed I think). I could see this as the beginning of a modern series of fables